This application is a request for continued support (in part) for the EORTC Data Center and Coordinating Office managed by M. Staquet, MD, MS, Clinical Coordinator of EORTC. The EORTC Data Center is a service organization for all clinical cooperative groups of EORTC. It conceives and organizes multicenter trials, collects and analyzes trial data which are made available to NCI whenever requested (198 multicenter trials in progress in 1986). The Data Center has also a coordinating function between European and U.S. centers and more specifically with NCI. It plays a central role in phase II-III trials performed with NSC drugs not tested in the U.S. Finally, the EORTC Data Center has its own research program in applied statistics, methodology of clinical trials, and clinical research.